In the manufacture of tires, various irregularities and variations in the dimensions of the tires can arise. For example, dimensional irregularities can arise from inaccuracies in the molding process, changes in the characteristics of the materials and compounds employed in manufacturing the tires, inaccurate centering and variations in the vulcanization process, etc. All of the possible irregularities and variations in the tires, which can arise during manufacture either singularly or through interaction with one another, can cause eccentricity, static and dynamic unbalance in the tire, and force variation which can result in tire vibration or noise during use.
It is possible to correct many of these irregularities by first measuring the tire variations and applying various corrective actions to the tire. To measure the variations, the tire is placed in a tire uniformity inspection machine. In currently available tire uniformity inspection machines, testing is fully automatic. Tires are fed by conveyor to a testing station where each tire is mounted upon a chuck apparatus, inflated to a predetermined pressure and rotatably driven at a standard speed with its tread surface abutting the circumferential surface of a loadwheel. The loadwheel is instrumented with load cells that measure forces due to the tire acting on the loadwheel in directions of interest. The data gathered during the testing process may be used to take immediate corrective action via shoulder and tread grinders, which selectively grind rubber from regions of the tire to compensate for the variations detected during the testing process. Alternately, or additionally, the data taken during the testing process may be used to mark specific regions of the tire to alert the buyer/installer to an area of interest, such as an irregularity or point of high force in the tire, which will enable the installer to take corrective or compensating action during installation of the tire onto a wheel.
In the typical tire uniformity testing machine available today, a vertically-movable lower rim is supported in the base of the machine and is mounted for movement toward and away from a rim fixed to the top of the machine. An elaborate framework including a plurality of spaced apart columns supports the tire testing equipment as well as the sensing, grinding and marking equipment. Many of the current machines when fully outfitted with a full compliment of subassemblies are very difficult to service and require great effort to convert from one tire size to another. In at least some of the currently available machines, the various subcomponents, such as grinders, sensors and marking equipment, are not well integrated because they were added to the basic structure over the course of time. Cabling for both power and control signals between the various components and a basic control panel can be very complex and difficult to troubleshoot should problems arise.
In still other testing machines, the level at which tires are tested at the testing station is well above the plant floor so as to require maintenance workers and operators to use auxiliary equipment, such as ladders or other devices, to reach componentry needing adjustment or service.
Further, known testing machines are somewhat limited in flexibility in that they are not easily adapted for use in a variety of manufacturing environments. Once assembled, conventional testing machines typically do not permit changes in the direction tires are moved through the machine, at least not without substantial alteration or rearrangement of the machine components. One reason it is difficult to change the direction of tire flow through known machines is that the inlet conveyor typically is fixed to or forms part of the testing station; therefore, it is either impossible or impractical to alter the machine so as to permit the tires to be input at the opposite end of the machine. However, it may be necessary or desirable to provide users with the option of selecting different tire input directions due to, for example, different manufacturing plant layouts or the need to modify an existing plant layout.
Another problem that may arise due to the inlet conveyor being fixed to or part of the testing machine is that the loadwheel may produce erroneous or inaccurate uniformity measurements as a result of disturbances at the inlet conveyor. For example, physical disturbances at or near the inlet conveyor may be transmitted to the testing station so as to adversely affect test results, e.g., by impacting the readings generated by the load cells carried by the loadwheel, the result of such disturbances being inaccurate or inconsistent uniformity determinations. Accordingly, there is a need in the art for an improved inlet conveyor suitable for use in tire testing machines which provides increased flexibility and accurate, consistent force readings relative to existing inlet conveyors.